Magnetic memory device

ABSTRACT

A magnetic memory device is provided. The magnetic memory device includes a first vertical magnetic layer and a second vertical magnetic layer on a substrate, a tunnel barrier layer between the fist vertical magnetic layer and the second vertical magnetic layer, and an exchange-coupling layer between a first sub-layer of the first vertical magnetic layer and a second sub-layer of the first vertical magnetic layer.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application claims priority as acontinuation application of U.S. patent application Ser. No. 13/091,215,filed Apr. 21, 2011, which in turn claims priority under 35 U.S.C. §119of Korean Patent Application No. 10-2010-0037017, filed on Apr. 21,2010, the entire contents of each of which are hereby incorporatedherein by reference.

BACKGROUND

The present disclosure herein relates to semiconductor devices and, morespecifically, to magnetic memory devices.

With the advent of high-speed and low-power consumption electronicdevices, built-in memory devices are required that can perform fast readand write operations and that have a low operating voltage. Magneticmemory devices have been studied as memory devices that may meet theserequirements. Due to their high-speed operation and non-volatilecharacteristics, magnetic memory devices have been hailed as a potentialnext generation memory device.

A magnetic memory device may include a Magnetic Tunnel Junction (MTJ)pattern. An MTJ pattern may be formed by two (2) magnetic layers with adielectric layer interposed therebetween and may have a differentresistivity depending on the magnetization directions of the twomagnetic layers. Specifically, an MTJ pattern may have a highresistivity when the magnetization direction of the two magnetic layersare anti-parallel to each other and may have a lower resistivity whenthe magnetization direction of the two magnetic layers are parallel toeach other. This difference in resistivity may be used to store data ina magnetic memory device.

SUMMARY

Embodiments of the present inventive concept may provide improvedmagnetic memory devices. Some of the embodiments disclosed herein mayprovide highly reliable magnetic memory devices and/or magnetic memorydevices that exhibit an increased lifetimes.

In some embodiments, magnetic memory devices are provided that include afirst vertical magnetic layer and a second vertical magnetic layer, thesecond vertical magnetic layer including a first sub-layer and a secondsub-layer, a tunnel barrier layer between the first vertical magneticlayer and the second vertical magnetic layer; and an exchange-couplinglayer between the first sub-layer and the second sub-layer.

The magnetic memory device may further comprise a first contact magneticlayer between the tunnel barrier layer and the first vertical magneticlayer and a second contact magnetic layer between the tunnel barrierlayer and the second vertical magnetic layer.

The magnetic memory device may further comprise a first additionalexchange-coupling layer between the second contact magnetic layer andthe second vertical magnetic layer.

The magnetic memory device may further comprise a second additionalexchange-coupling layer between the first contact magnetic layer and thefirst vertical magnetic layer.

The first vertical magnetic layer may include a first sub-layer and asecond sub-layer, and the magnetic memory device may further comprise athird additional exchange-coupling layer between the first sub-layer ofthe first vertical magnetic layer and the second sub-layer of the firstvertical magnetic layer.

The magnetic memory device may further comprise a diffusion barrierlayer between the second vertical magnetic layer and the second contactmagnetic layer.

The first sub-layer of the second vertical magnetic layer may includealternately and repeatedly stacked non-magnetic layers and ferromagneticlayers, and the diffusion barrier layer may be in contact with theferromagnetic layer of the first sub-layer.

The ferromagnetic layer of the first sub-layer in contact with thediffusion barrier layer may comprise a different material from the restof the ferromagnetic layers in the first sub-layer.

The magnetic memory device may further comprise an additional diffusionbarrier between the first vertical magnetic layer and the first contactmagnetic layer.

The respective first sub-layer and second sub-layer may comprisealternately and repeatedly stacked non-magnetic layers and ferromagneticlayers; the exchange-coupling layer may comprise a first surface and asecond surface, the surfaces being opposite to each other; and the firstsurface of the exchange-coupling layer may be in contact with theferromagnetic layer of the first sub-layer and the second surface of theexchange-coupling layer may be in contact with the ferromagnetic layerof the second sub-layer.

The ferromagnetic layer in contact with the first surface may be thickerthan the rest of the respective ferromagnetic layers in the firstsub-layer, and the ferromagnetic layer in contact with the secondsurface may be thicker than the rest of the respective ferromagneticlayers in the second sub-layer.

The ferromagnetic layer in contact with the first surface may comprise adifferent material from the rest of the ferromagnetic layers in thefirst sub-layer, and the ferromagnetic layer in contact with the secondsurface may comprise a different material from the rest of theferromagnetic layers in the first sub-layer.

The ferromagnetic layer of the first sub-layer in contact with the firstsurface may comprise a same material as the ferromagnetic layer of thesecond sub-layer in contact with the second surface.

One of the first vertical magnetic layer and the second verticalmagnetic layer may be a reference layer and the other one may be a freelayer.

The second vertical magnetic layer may be a reference layer.

The exchange-coupling layer may be 2Å to 18Å thick.

According to the present inventive concept, an exchange-coupling layeris interposed between a first sub-layer and a second sub-layer, whichare contained in the second vertical magnetic layer. As a result, amagnetic memory device can stably maintain magnetization directions,thereby achieving a highly reliable magnetic memory device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross sectional view illustrating a magnetic memory deviceaccording to a first example embodiment of the present inventiveconcept.

FIG. 1B is a cross sectional view illustrating a vertical magnetic layerthat is included in the magnetic memory device according to the firstexample embodiment of the present inventive concept.

FIG. 2A is a cross sectional view illustrating a magnetic memory deviceaccording to a modified version of the first example embodiment of thepresent inventive concept.

FIGS. 2B through 2C are cross sectional views illustrating a verticalmagnetic layer that is included in the magnetic memory device accordingto the modified version of the first example embodiment of the presentinventive concept.

FIG. 3A is a cross sectional view illustrating a magnetic memory deviceaccording to a second example embodiment of the present inventiveconcept.

FIG. 3B is a cross sectional view illustrating a vertical magnetic layerthat is included in the magnetic memory device according to the secondexample embodiment of the present inventive concept.

FIG. 4 is a cross sectional view illustrating a magnetic memory deviceaccording to a modified version of the second example embodiment of thepresent inventive concept.

FIG. 5A is a cross sectional view illustrating a magnetic memory deviceaccording to a third example embodiment of the present inventiveconcept.

FIG. 5B is a cross sectional view illustrating a vertical magnetic layerthat is included in the magnetic memory device according to the thirdexample embodiment of the present inventive concept.

FIG. 6A is a cross sectional view illustrating a magnetic memory deviceaccording to a fourth example embodiment of the present inventiveconcept.

FIG. 6B is a cross sectional view illustrating a vertical magnetic layerthat is included in the magnetic memory device according to the fourthexample embodiment of the present inventive concept.

FIG. 7 is a cross sectional view illustrating a magnetic memory deviceaccording to a modified version of the fourth example embodiment of thepresent inventive concept.

FIG. 8 is a cross sectional view illustrating a magnetic memory deviceaccording to a fifth example embodiment of the present inventiveconcept.

FIG. 9A is a cross sectional view illustrating a magnetic memory deviceaccording to a sixth example embodiment of the present inventiveconcept.

FIG. 9B is a cross sectional view illustrating a vertical magnetic layerthat is included in the magnetic memory device according to the sixthexample embodiment of the present inventive concept.

FIG. 10 is a block diagram illustrating an electronic system thatincludes a magnetic memory device according to example embodiments ofthe present inventive concept.

FIG. 11 is a block diagram illustrating a memory card that includes amagnetic memory device according to example embodiments of the presentinventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, example embodiments of the present inventive concept willbe explained in detail with reference to the accompanying drawings. Theembodiments of the present inventive concept may, however, be embodiedin different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the inventive concept to those skilled in the art.

It will be understood that when a film (or a layer) is referred to asbeing “on” another film (or a layer), it can be directly on the otherfilm or intervening elements may also be present. In the drawings, thesizes and thicknesses of films (or layers) and regions may beexaggerated for clarity. It will be understood that, although the termsfirst, second, third, etc. may be used herein to describe variousregions and films (or layers), these regions and films should not belimited by these terms. These terms are only used to distinguish oneregion or one film (or a layer) from another region or another film (oranother layer). Thus, a first film in some embodiments could be termed asecond film in other embodiments. It will also be understood thatexemplary embodiments of the present inventive concept explained andillustrated herein include their complementary counterparts. The term“and/or” in this specification is used to refer to include at least oneof an associated listed items. Like reference numerals in thisspecification refer to like elements throughout.

Hereinafter, a magnetic memory device according to the first exampleembodiment of the present inventive concept will be explained. FIG. 1Ais a cross sectional view of the magnetic memory device according to thefirst example embodiment of the present inventive concept, and FIG. 1Bis a cross sectional view of a vertical magnetic layer that is includedin the magnetic memory device according to the first example embodimentof the present inventive concept.

Referring to FIG. 1A, a first vertical magnetic layer 130 and a secondvertical magnetic layer 150 may be disposed on a substrate 100. A tunnelbarrier layer 110 may be interposed between the first and secondvertical magnetic layers 130, 150. The second vertical magnetic layer150 may comprise a first sub-layer 152 and a second sub-layer 154. Anexchange coupling layer 160 may be interposed between the firstsub-layer 152 and the second sub-layer 154. An MTJ pattern may comprisethe first vertical magnetic layer 130, the tunnel barrier layer 110, andthe second vertical magnetic layer 150. A lower electrode 105 may bedisposed between the MTJ pattern and the substrate 100.

As illustrated, the first vertical magnetic layer 130, the tunnelbarrier layer 110, and the second vertical magnetic layer 150 may besequentially stacked on the lower electrode 105. However, the presentinventive concept is not so limited. According to another embodiment ofthe present inventive concept, the second vertical magnetic layer 150,the tunnel barrier layer 110, and the first vertical magnetic layer 130may be sequentially stacked on the lower electrode 105. Hereinafter, forthe sake of convenience, the present inventive concept will be explainedwith reference to an embodiment in which the first vertical magneticlayer 130, the tunnel barrier layer 110, and the second verticalmagnetic layer 150 are sequentially stacked on the lower electrode 105.

The substrate 100 may comprise a semiconductor substrate and adielectric layer that is formed on the semiconductor substrate. Thelower electrode 105 may be disposed on the dielectric layer included inthe substrate 100. The substrate 100 may further comprise a contact plug(not shown) in the dielectric layer. The lower electrode 105 may beconfigured to electrically connect to the contact plug.

The tunnel barrier layer 110 may be disposed on the substrate 100. Thetunnel barrier layer 110 may comprise an insulating material. Forexample, in some embodiments, the tunnel barrier layer 110 may compriseat least one selected from the group consisting of magnesium oxide(MgO), titanium oxide (TiO), aluminum oxide (AlO), magnesium-zinc oxide(MgZnO), magnesium-boron oxide (MgBO), titanium nitride (TiN), orvanadium nitride (VN). The tunnel barrier layer 110 may be formed ofmultiple layers. For example, in some embodiments, the tunnel barrierlayer 110 may be magnesium/magnesium oxide (Mg/MgO), magnesiumoxide/magnesium (MgO/Mg), or magnesium/magnesium oxide/magnesium(Mg/MgO/Mg). The tunnel barrier layer 110 may have a thickness that isthinner than the spin diffusion distance. For example, the tunnelbarrier 110 may be a magnesium oxide (MgO) layer having a thickness ofapproximately 10Å.

The first vertical magnetic layer 130 may be disposed on (eitherdirectly or indirectly) a first surface of the tunnel barrier layer 110and the second vertical magnetic layer 150 may be disposed on a secondsurface of the tunnel barrier layer 110, which is opposite the firstsurface. In the case that programming current flows in a perpendiculardirection with respect to a top surface of the substrate 100, the firstvertical magnetic layer 130 and the second vertical magnetic layer 150may be constructed to have a magnetization direction that is paralleland/or anti-parallel to the programming current.

The first vertical magnetic layer 130 may include alternately andrepeatedly stacked ferromagnetic layers and non-magnetic layers. Forexample, the ferromagnetic layers included in the first verticalmagnetic layer 130 may comprise at least one selected from the groupconsisting of iron (Fe), cobalt (Co), or nickel (Ni), and thenon-magnetic layers included in the first vertical magnetic layer 130may comprise at least one selected from the group consisting of chromium(Cr), platinum (Pt), palladium (Pd), iridium (Ir), ruthenium (Ru),rhodium (Rh), osmium (Os), rhenium (Re), gold (Au), or copper (Cu).

For example, the first vertical magnetic layer 130 may comprise[Co/Pt]_(m), [Co/Pd]_(m) or a combination thereof. The non-magneticlayer and ferromagnetic layers included in the first vertical magneticlayer 130 may be stacked, for example, two (2) to twenty (20) times. Theferromagnetic layers included in the first vertical magnetic layer 130may be very thin layers having a thickness of a single to several atomiclayers. A seed layer may be interposed between the lower electrode 105and the first vertical magnetic layer 130.

The second vertical magnetic layer 150 may comprise a first sub-layer152 and a second sub-layer 154. An exchange-coupling layer 160 may beinterposed between the first sub-layer 152 and the second sub-layer 154.The exchange-coupling layer 160 may have a first surface and a secondsurface that is opposite the first surface. The first sub-layer 152 maycontact the first surface of the exchange-coupling layer 160 and thesecond sub-layer 154 may contact the second surface of theexchange-coupling layer 160. A magnetization direction of the firstsub-layer 152 and a magnetization direction of the second sub-layer 154may be exchange-coupled in anti-parallel by the exchange-coupling layer160. As a result, the second vertical magnetic layer 150 may have twomagnetization directions, which are anti-parallel to each other. Forexample, in the case that the first sub-layer 152 has a magnetizationdirection of a first direction, the second sub-layer 154 may have amagnetization direction of a second direction that is anti-parallel withthe first direction.

For example, the exchange-coupling layer 160 may comprise ruthenium(Ru), rhodium (Rh), chromium (Cr), and/or iridium (Ir). Theexchange-coupling layer 160 may be approximately 2 Å to approximately 18Å thick in some embodiments.

The first sub-layer 152 and the second sub-layer 154 may comprisealternately and repeatedly stacked non-magnetic layers and ferromagneticlayers. This will be explained in more detail with reference to FIG. 1B,

Referring FIG. 1B, the first sub-layer 152 may comprise alternately andrepeatedly stacked ferromagnetic layers 152 aU, 152 a, and non-magneticlayers 152 bU, 152 b. The first surface of the exchange-coupling layer160 may contact the uppermost ferromagnetic layer 152 aU among theferromagnetic layers 152 a, 152 aU included in the first sub-layer 152.The uppermost ferromagnetic layer 152 aU may be thicker than the rest ofthe ferromagnetic layers 152 a that are included in the first sub-layer152. The thicknesses of the rest of the ferromagnetic layers 152 a maybe substantially the same. For example, the uppermost ferromagneticlayer 152 aU may be approximately 5 Å thick and the rest of theferromagnetic layers 152 a may be approximately 2 Å thick. Theferromagnetic layers 152 a, 152 aU may comprise the same material. Forexample, the ferromagnetic layers 152 a, 152 aU may comprise cobalt(Co).

The uppermost non-magnetic layer 152 bU of the first sub-layer 152adjoining the first surface of the exchange-coupling layer 160 maycomprise a different material from the rest of the non-magnetic layers152 b . The rest of the non-magnetic layers 152 b may each be formed ofthe same material. For example, the uppermost non-magnetic layers 152 bUmay comprise platinum (Pt), while the rest of the non-magnetic layers152 b may comprise palladium (Pd). Although the ferromagnetic layers 152aU, 152 a and non-magnetic layers 152 bU, 152 b are stacked 4 times inthe drawing, they can alternatively be stacked 2 times, 3 times or morethan 5 times.

The second sub-layer 154 may comprise alternately and repeatedly stackedferromagnetic layers 154 aL, 154 a, and non-magnetic layers 154 bL, 154b . The second surface of the exchange-coupling layer 160 may contactthe lowermost ferromagnetic layer 154 aL among the ferromagnetic layers154 aL, 154 a included in the second sub-layer 154. The lowermostferromagnetic layer 154 aL may be thicker than the rest of theferromagnetic layers 154 a that are included in the second sub-layer154. The thicknesses of the rest of the ferromagnetic layers 154 a maybe substantially the same. For example, the lowermost ferromagneticlayer 154 aL may be approximately 5 Å thick and the rest of theferromagnetic layers 154 a may be approximately 2 Å thick. Theferromagnetic layers 154 a, 154 aL may comprise the same material. Forexample, the ferromagnetic layers 154 aL, 154 a may comprise cobalt(Co).

The lowermost non-magnetic layer 154 bL of the second sub-layer 154adjoining the second surface of the exchange-coupling layer 160 maycomprise a different material from the rest of the non-magnetic layers154 b . The rest of the non-magnetic layers 154 b may each be formed ofthe same material. For example, the lowermost non-magnetic layers 152 bLmay comprise platinum (Pt), while the rest of the non-magnetic layers154 b may comprise palladium (Pd). Although the ferromagnetic layers 154aL, 154 a and non-magnetic layers 154 bL, 154 b are stacked 4 times inthe drawing, they can be stacked 2 times, 3 times or more than 5 timesin other embodiments.

One of the first vertical magnetic layer 130 and the second verticalmagnetic layer 150 can be used as a reference layer and the other onemay be used as a free layer of a magnetic memory cell. The number ofstacking times of non-magnetic and ferromagnetic layers of the firstvertical magnetic layer 130 may be different from the number of stackingtimes of non-magnetic and ferromagnetic layers of the first and secondsub layers 152, 154 in the second vertical magnetic layer 150. Accordingto the difference of these stacking times, the first vertical magneticlayer 130 and the second vertical magnetic layer 150 may be divided intoa free layer and a reference layer. For example, the number of stackingtimes of non-magnetic and ferromagnetic layers of the first verticalmagnetic layer 130 may be larger than the number of stacking times ofnon-magnetic and ferromagnetic layers of the first and second sub layers152, 154. In this case, the first vertical magnetic layer 130 may be afree layer and the second vertical magnetic layer 150 may be a referencelayer.

Referring again to FIG. 1A, a first contact magnetic layer 120 may bedisposed between the tunnel barrier layer 110 and the first verticalmagnetic layer 130, and a second contact magnetic layer 140 may bedisposed between the tunnel barrier layer 110 and the second verticalmagnetic layer 150. The tunnel barrier layer 110 may be disposed betweenthe first contact magnetic layer 120 and the second contact magneticlayer 140. A magnetization direction of the first contact magnetic layer120 may be exchange-coupled in parallel with a magnetization directionof the first vertical magnetic layer 130, thereby having the samemagnetization direction as the first vertical magnetic layer 130. Amagnetization direction of the second contact magnetic layer 140 may beexchange-coupled in parallel with a magnetization direction of the firstsub-layer 152, thereby having the same magnetization direction as thefirst sub-layer 152.

Any one contact magnetic layer of the first contact magnetic layer 120and the second contact magnetic layer 140 can be used as a referencelayer and the other one may be used as a free layer of a magnetic memorycell. For example, in the case that the first vertical magnetic layer130 is used as a free layer and the second vertical magnetic layer 150is used as a reference layer, the first contact magnetic layer 120 canbe used as a free layer and the second contact magnetic layer 140 can beused as a reference layer.

The first contact magnetic layer 120 and the second contact magneticlayer 140 may each comprise a soft magnetic material. The saturationmagnetization quantity of the contact magnetic layer being used as areference layer may be larger than the saturation magnetization quantityof the contact magnetic layer being used as a free layer. The differencein the saturation magnetization quantity between the reference layer andthe free layer can be adjusted depending on the contents offerromagnetic materials contained in the first contact magnetic layer120 and in the second contact magnetic layer 140, respectively. In thecase where the first contact magnetic layer 120 is used as a free layerand the second contact magnetic layer 140 is used as a reference layer,the content of ferromagnetic materials contained in the first contactmagnetic layer 120 may be lower than the content of ferromagneticmaterials contained in the second contact magnetic layer 140.Conversely, in the case where the first contact magnetic layer 120 isused as a reference layer and the second contact magnetic layer 140 isused as a free layer, the content of ferromagnetic materials containedin the first contact magnetic layer 120 may be higher than the contentof ferromagnetic materials contained in the second contact magneticlayer 140. For example, the ferromagnetic material may comprise cobalt(Co), iron (Fe), and/or nickel (Ni).

As mentioned in the foregoing, the difference in the saturationmagnetization quantity between the reference layer and the free layercan be adjusted depending on the contents of non-magnetic materialscontained in the first contact magnetic layer 120 and the second contactmagnetic layer 140. In the case where the first contact magnetic layer120 is used as a free layer and the second contact magnetic layer 140 isused as a reference layer, the content of non-magnetic materialscontained in the first contact magnetic layer 120 may be lower than thecontent of non-magnetic materials contained in the second contactmagnetic layer 140. Conversely, in the case where the first contactmagnetic layer 120 is used as a reference layer and the second contactmagnetic layer 140 is used as a free layer, the content of non-magneticmaterials contained in the first contact magnetic layer 120 may behigher than the content of non-magnetic materials contained in thesecond contact magnetic layer 140. For example, the non-magneticmaterial may comprise titanium (Ti), aluminum (Al), silicon (Si),magnesium (Mg), and/or tantalum (Ta).

The first contact magnetic layer 120 and the second contact magneticlayer 140 may have high spin polarization rates and low dampingcoefficients. The first contact magnetic layer 120 and the secondcontact magnetic layer 140 may further comprise at least one selectedfrom the group of non-magnetic materials consisting of boron (B), zinc(Zn), ruthenium (Ru), silver (Ag), gold (Au), copper (Cu), carbon (C)and nitrogen (N). For example, the first contact magnetic layer 120 andthe second contact magnetic layer 140 may comprise CoFe or NiFe and mayfurther include boron.

A capping layer 180 may be provided on the second vertical magneticlayer 150. The capping layer 180 may comprise, for example, tantalum(Ta), aluminum (Al), copper (Cu), gold (Au), silver (Ag), titanium (Ti),tantalum nitride (TaN), and/or titanium nitride (TiN).

The contact magnetic layers 120, 140 and the tunnel barrier layer 110may be included in the MTJ pattern. Data can be stored in a magneticmemory device by using the resistivity difference according to beingparallel or anti-parallel of the magnetization directions of the contactmagnetic layers 120, 140.

For example, the first contact magnetic layer 120 can be a free layerand the second contact magnetic layer 140 can be a reference layer. Inthe case where electrons move from the first contact magnetic layer 120into the second contact magnetic layer 140, electrons having a spin of afirst magnetization direction, which is parallel to the second contactmagnetic layer 140, may pass through the tunnel barrier layer 110. Onthe other hand, most of electrons having a spin of a secondmagnetization direction, which is anti-parallel to the second contactmagnetic layer 140, may not pass through the tunnel barrier layer 110but instead are reflected, and thereby remain within the first contactmagnetic layer 120.

Due to the electrons that remain in the first contact magnetic layer 120having a spin of the second direction, a magnetization direction of thefirst contact magnetic layer 120 may be a second direction. Accordingly,the first contact magnetic layer 120 and the second contact magneticlayer 140 may have magnetization directions that are opposite to eachother and, as a result, the MTJ may have a relatively high firstresistance value.

Conversely, in the case where the first contact magnetic layer 120 is afree layer and the second contact magnetic layer 140 is a referencelayer, electrons move from the second contact magnetic layer 140 intothe first contact magnetic layer 120. Due to the electrons having a spinof a first direction arriving at the first contact magnetic layer 120,the first contact magnetic layer may have a magnetization direction ofthe first direction. Accordingly, in this case, the MTJ may have arelatively low second resistance value.

As disclosed in the foregoing, depending on the directions of electronsflowing along the MTJ, the resistance value of the MTJ may vary, andusing this resistivity difference, data can be stored in a magneticmemory cell.

According to the magnetic memory device explained above, theexchange-coupling layer 160 may be disposed within the second verticalmagnetic layer 150. Due to this, mutual coupling force, themagnetization directions of the second vertical magnetic layer 150 maybe stably maintained. Accordingly, a mutual interference phenomenabetween the first vertical magnetic layer 130 and the second verticalmagnetic layer 150 may be reduced and/or minimized. As a result,magnetization directions of a magnetic memory device including the firstand the second vertical magnetic layers 130, 150 may be stablymaintained, thereby achieving a highly reliable magnetic memory device.

In a magnetic memory device according to the aforementioned firstexample embodiment of the present inventive concept, diffusion barrierlayers can be interposed between the first contact magnetic layer 120and the first vertical magnetic layer 130 and between the second contactmagnetic layer 140 and the second vertical magnetic layer 150. This willbe explained with reference to FIG. 2A.

FIG. 2A is a cross sectional view illustrating a magnetic memory deviceaccording to a modified version of the first example embodiment of thepresent inventive concept. FIG. 2B is a cross sectional viewillustrating a second vertical magnetic layer that is included in themagnetic memory device of FIG. 2A. FIG. 2C is a cross sectional viewillustrating a first vertical magnetic layer that is included in themagnetic memory device of FIG. 2A.

Referring to FIG. 2A, as explained above with reference to FIG. 1A, alower electrode 105, a first contact magnetic layer 120, a tunnelbarrier layer 110, a second contact magnetic layer 140 and a cappinglayer 180 can be provided on a substrate 100.

A first vertical magnetic layer 132 may be disposed between the lowerelectrode 105 and the first contact magnetic layer 120. In the casewhere the current flows in a perpendicular direction with respect to thesubstrate 100, the first vertical magnetic layer 132 may be constructedto have a magnetization direction parallel and/or anti-parallel with thecurrent.

A first diffusion barrier layer 172 may be disposed between the firstvertical magnetic layer 132 and the first contact magnetic layer 120.The first diffusion barrier layer 172 may have a first surface and asecond surface that is opposite the first surface. The first surface ofthe first diffusion barrier layer 172 may be in contact with the firstvertical magnetic layer 132, and the second surface of the firstdiffusion barrier layer 172 may be in contact with the first contactmagnetic layer 120. The first diffusion barrier layer 172 may minimizethe diffusion of constituent elements of the first contact magneticlayer 120 into the first vertical magnetic layer 132. For example, inthe case where the first contact magnetic layer 120 is formed of cobalt(Co), iron (Fe), and/or boron (B), the first diffusion barrier layer 172may reduce and/or minimize the diffusion of boron (B) in the firstcontact magnetic layer 120 into the first vertical magnetic layer 132.Due to this reduced diffusion, the vertical magnetic unisotropy of thefirst contact magnetic layer 120 can be improved. The vertical magneticunisotropy is a magnetic layer's characteristic to be magnetized in aperpendicular direction with respect to the substrate 100.

In some embodiments, the first diffusion barrier layer 172 may comprisetantalum (Ta), hafnium (Hf), zirconium (Zr), titanium (Ti), tantalumoxide, hafnium oxide, zirconium oxide, titanium oxide, aluminum oxide,and/or manganese oxide. The first diffusion barrier layer 172 can be,for example, approximately 2 Å to approximately 10 Å thick.

The first vertical magnetic layer 132 may comprise alternately andrepeatedly stacked non-magnetic and ferromagnetic layers. This will beexplained in more detail with reference to FIG. 2C.

Referring to FIG. 2C, the first vertical magnetic layer 132 may comprisealternately and repeatedly stacked ferromagnetic layers 132 aU, 132 aand non-magnetic layers 132 bU, 132 b . The first surface of the firstdiffusion barrier layer 172 may contact the uppermost ferromagneticlayer 132 aU among the ferromagnetic layers 132 aU, 132 a that areincluded in the first vertical magnetic layer 132. The ferromagneticlayers 132 aU, 132 a may comprise the same material. For example, theferromagnetic layers 132 aU, 132 a may comprise cobalt (Co). Theferromagnetic layers 132 aU, 132 a may be approximately 2 Å thick.

The uppermost non-magnetic layer 132 bU of the first vertical magneticlayer 132 adjoining the first surface of the first diffusion barrierlayer 172 may comprise a different material from the rest of thenon-magnetic layers 132 b, The rest of the non-magnetic layers 132 b maycomprise the same material. For example, the uppermost non-magneticlayers 132 bU may comprise platinum (Pt), while the rest of thenon-magnetic layers 132 b may comprise palladium (Pd).

Referring again to FIG. 2A, the second vertical magnetic layer 151 maybe disposed between the second contact magnetic layer 140 and thecapping layer 180. In the case where the current flows in aperpendicular direction with respect to a top surface of the substrate100, the second vertical magnetic layer 151 may be constructed to have amagnetization direction parallel and/or anti-parallel with the current.

A second diffusion barrier layer 174 may be disposed between the secondvertical magnetic layer 151 and the second contact magnetic layer 140.The second diffusion barrier layer 174 may have a first surface and asecond surface that is opposite the first surface. The first surface ofthe second diffusion barrier layer 174 may contact the second verticalmagnetic layer 151 and the second surface of the second diffusionbarrier layer 174 may contact the second contact magnetic layer 140, Thesecond diffusion barrier layer 174 may reduce and/or minimize thediffusion of constituent elements of the second contact magnetic layer140 into the second vertical magnetic layer 151. For example, in thecase where the second contact magnetic layer 140 is formed of cobalt(Co), iron (Fe), and boron (B), the diffusion of boron (B) in the secondcontact magnetic layer 140 into the second vertical magnetic layer 151can be reduced and/or minimized. Due to this reduction in diffusion ofelements from the second contact magnetic layer 140 into the secondvertical magnetic layer 151, vertical magnetic unisotropy of the secondcontact magnetic layer 140 can be improved. The second diffusion barrierlayer 174 may comprise the same material as the first diffusion barrierlayer 172.

The second vertical magnetic layer 151 may comprise a first sub-layer153 and a second sub-layer 154. An exchange-coupling layer 160 may beinterposed between the first sub-layer 153 and the second sub-layer 154,as explained above with reference to FIG. 1A.

The first sub-layer 153 and the second sub-layer 154 may comprisealternately and repeatedly stacked non-magnetic layers and ferromagneticlayers. This will be explained with reference to FIG. 2B.

Referring to FIG. 2B, the first sub-layer 153 may comprise alternatelyand repeatedly stacked ferromagnetic layers 153 aL, 153 a, 153 aU andnon-magnetic layers 153 bL, 153 b, 153 bU. A first surface of theexchange-coupling layer 160 may directly contact the uppermostferromagnetic layer 153 aU among the ferromagnetic layers 153 aL, 153 a,153 aU included in the first sub-layer 153. The uppermost ferromagneticmaterial 153 aU may be thicker than the rest of the ferromagnetic layers153 a, 153 aL. The uppermost non-magnetic layer 153 bU and the lowermostnon-magnetic layer 153 bL of the first sub-layer 153 may comprise adifferent material from the rest of the non-magnetic layers 153 b.

The first surface of the second diffusion barrier layer 174 may contactthe lowermost ferromagnetic layer 153 aL among the ferromagnetic layers153 aL, 153 a, 153 aU included in the first sub-layer 153. The lowermostnon-magnetic layer 153 bL of the first sub-layer 153 adjoining thesecond diffusion barrier layer 174 may comprise the same material as theuppermost non-magnetic layer 153 bU.

The second sub-layer 154 in the device of FIGS. 2A-2C may be identicalto the second sub-layer 154 of the device of FIGS. 1A-1B, and hencefurther description thereof will be omitted herein.

According to a modification of the first example embodiment of thepresent inventive concept, either one of the first diffusion barrierlayer 172 or the second diffusion barrier layer 174 may be omitted.

In the aforementioned first example embodiment of the present inventiveconcept, the exchange-coupling layer 160 is disposed between the firstsub-layer 153 and the second sub-layer 154 of the second verticalmagnetic layer 151. In other embodiments, however, the exchange-couplinglayer may instead be interposed between the contact magnetic layer andthe vertical magnetic layer. This will be explained with reference toFIG. 3A.

FIG. 3A is a cross sectional view illustrating a magnetic memory deviceaccording to a second example embodiment of the present inventiveconcept. FIG. 3B is a cross sectional view illustrating a verticalmagnetic layer that is included in the magnetic memory device accordingto the second example embodiment of the present inventive concept.

Referring to FIG. 3A, as explained referring to FIG. 1A, a lowerelectrode 105, a first vertical magnetic layer 130, a first contactmagnetic layer 120, a tunnel barrier layer 110, a second contactmagnetic layer 140 and a capping layer 180 can be provided on asubstrate 100. Since the above-referenced layers of the device of FIGS.3A-3B are identical to the correspondingly numbered layers of the deviceof FIGS. 1A-1B, further description thereof will be omitted.

A second vertical magnetic layer 156 may be disposed between the secondcontact magnetic layer 140 and the capping layer 180. Anexchange-coupling layer 162 may be disposed between the second verticalmagnetic layer 156 and the second contact magnetic layer 140. A firstsurface of the exchange-coupling layer 162 may contact the secondvertical magnetic layer 156, and a second surface of theexchange-coupling layer 162 that is opposite the first surface maycontact the second contact magnetic layer 140. A magnetization directionof the second vertical magnetic layer 156 and a magnetization directionof the second contact magnetic layer 140 may be exchange-coupled inanti-parallel by the exchange-coupling layer 162. The exchange-couplinglayer 162 may comprise the same material as the exchange-coupling layer160, which was discussed above with reference to FIG. 1A.

As shown in FIG. 3B, the second vertical magnetic layer 156 may comprisealternately and repeatedly stacked ferromagnetic layers 156 aL, 156 a,and non-magnetic layers 156 bL, 156 b . The first surface of theexchange-coupling layer 162 may contact the lowermost ferromagneticlayer 156 aL among the ferromagnetic layers 156 aL, 156 a included inthe second vertical magnetic layer 156. The lowermost ferromagneticlayer 156 aL may be thicker than the rest of the ferromagnetic layers156 a included in the second vertical magnetic layer 156. Thethicknesses of the rest of the ferromagnetic layers 156 a may besubstantially the same. For example, the lowermost ferromagnetic layer156 aL may be approximately 5 Å thick and the rest of the ferromagneticlayers 156 a may be approximately 2 Å thick. The ferromagnetic layers156 a, 156 aL may comprise the same material. For example, theferromagnetic layers 156 a, 156 aL may comprise cobalt (Co).

The lowermost non-magnetic layer 156 bL of the second vertical magneticlayer 156 may comprise a different material from the rest of thenon-magnetic layers 156 b. The rest of the non-magnetic layers 156 b maycomprise a same material, For example, the lowermost non-magnetic layers156 bL may comprise platinum (Pt) and the rest of the non-magnetic layer156 b may comprise palladium (Pd).

A magnetic memory device according to the aforementioned second exampleembodiment of the present inventive concept may further include adiffusion layer between the first contact magnetic layer 120 and thefirst vertical magnetic layer 130. This modification to the device ofFIGS. 3A-3B will be explained with reference to FIG. 4.

FIG. 4 is a cross sectional view illustrating a magnetic memory deviceaccording to a modification of the second example embodiment of thepresent inventive concept.

Referring to FIG. 4, as explained above with reference to FIG. 1A, alower electrode 105, a first contact magnetic layer 120, a tunnelbarrier layer 110, a second contact magnetic layer 140 and a cappinglayer 180 can be provided on a substrate 100. Since the above-referencedlayers of the device of FIG. 4 are identical to the correspondinglynumbered layers of the device of FIGS. 1A-1B, further descriptionthereof will be omitted. Additionally, an exchange-coupling layer 162and a second vertical magnetic layer 156 may be disposed between thesecond contact magnetic layer 140 and the capping layer 180. Since theabove-referenced layers of the device of FIG. 4 are identical to thecorrespondingly numbered layers of the device of FIGS. 3A-3B, furtherdescription thereof will also be omitted.

A first vertical magnetic layer 132 may be disposed between the lowerelectrode 105 and the first contact magnetic layer 120. A diffusionbarrier layer 172 may be disposed between the first vertical magneticlayer 132 and the first contact magnetic layer 120. The first verticalmagnetic layer 132 may be identical to the vertical magnetic layer 132,which was discussed above with reference to FIG. 2C, and the diffusionbarrier layer 172 may be identical to the first diffusion barrier layer172, which was discussed above with reference to FIG. 2A.

According to the aforementioned second embodiment of the presentinventive concept, an exchange-coupling layer 162 can be interposedbetween the second vertical magnetic layer 156 and the second contactmagnetic layer 140. A second exchange-coupling layer may be furtherinterposed between the first vertical magnetic layer and the firstcontact magnetic layer 120. This will be explained with reference toFIGS. 5A and 5B.

FIG. 5A is a cross sectional view illustrating a magnetic memory deviceaccording to a third example embodiment of the present inventiveconcept. FIG. 5B is a cross sectional view illustrating a verticalmagnetic layer that is included in the magnetic memory device accordingto the third example embodiment of the present inventive concept.

Referring to FIG. 5A, as explained above with reference to FIG. 1A, alower electrode 105, a first contact magnetic layer 120, a tunnelbarrier layer 110, a second contact magnetic layer 140 and a cappinglayer 180 can be provided on a substrate 100.

A first vertical magnetic layer 133 may be disposed between the firstcontact magnetic layer 120 and the lower electrode 105. A firstexchange-coupling layer 162 may be disposed between the first verticalmagnetic layer 133 and the first contact magnetic layer 120. The firstvertical magnetic layer 133 may contact a first surface of the firstexchange-coupling layer 162, and the first contact magnetic layer 120may contact a second surface of the first exchange-coupling layer 162that is opposite the first surface.

A magnetization direction of the first vertical magnetic layer 133 and amagnetization direction of the first contact magnetic layer 120 may beexchange-coupled in anti-parallel by the first exchange-coupling layer162. The exchange-coupling layer 162 may comprise the same material asthe exchange-coupling layer 160, which was discussed above withreference to FIG. 1A.

The first vertical magnetic layer 133 may comprise alternately andrepeatedly stacked ferromagnetic and non-magnetic layers. This will beexplained with reference to FIG. 5B.

Referring to FIG. 5B, the first vertical magnetic layer 133 may comprisealternately and repeatedly stacked ferromagnetic layers 133 a, 133 aUand non-magnetic layers 133 b, 133 bU. The first surface of the firstexchange-coupling layer 162 may contact the uppermost ferromagneticlayer 133 aU among the ferromagnetic layers 133 a, 133 aU included inthe first vertical magnetic layer 133. The uppermost ferromagnetic layer133 aU may be thicker than the rest of the ferromagnetic layers 133 aincluded in the first vertical magnetic layer 133. The thicknesses ofthe rest of the ferromagnetic layers 133 a may be substantially thesame. For example, the uppermost ferromagnetic layer 133 aU may beapproximately 5 Å thick and the rest of the ferromagnetic layers 133 amay be approximately 2 Å thick. The uppermost ferromagnetic layer 133 aUmay comprise the same material as the rest of the ferromagnetic layer133 a . For example, the ferromagnetic layers 133 aU, 133 a may comprisecobalt (Co).

The uppermost non-magnetic layer 133 bU of the first vertical magneticlayer 133 may comprise a different material than the rest of thenon-magnetic layers 133 b . The rest of the non-magnetic layers 133 bmay comprise a same material. For example, the uppermost non-magneticlayers 133 bU may comprise platinum (Pt) and the rest of thenon-magnetic layers 133 b may comprise palladium (Pd).

A second vertical magnetic layer 156 may be disposed between the secondcontact magnetic layer 140 and the capping layer 180. A secondexchange-coupling layer 164 may be disposed between the second verticalmagnetic layer 156 and the second contact magnetic layer 140. The secondvertical magnetic layer 156 and the second exchange-coupling layer 164may comprise the same material as the second vertical magnetic layer 156and the exchange-coupling layer 162, respectively, of FIGS. 3A-3B.

According to the aforementioned first embodiment of the presentinventive concept, an exchange-coupling layer 160 can be interposedbetween the first sub-layer 152 and the second sub-layer 154 of thesecond vertical magnetic layer 150. Another exchange-coupling layer maybe further interposed between the second vertical magnetic layer 150 andthe second contact magnetic layer 140. This will be explained withreference to FIG. 6A.

FIG. 6A is a cross sectional view illustrating a magnetic memory deviceaccording to a fourth example embodiment of the present inventiveconcept. FIG. 6B is a cross sectional view illustrating a verticalmagnetic layer that is included in the magnetic memory device accordingto the fourth example embodiment of the present inventive concept.

Referring to FIG. 6A, as explained above with reference to FIG. 1A, alower electrode 105, a first vertical magnetic layer 130, a firstcontact magnetic layer 120, a tunnel barrier layer 110, a second contactmagnetic layer 140 and a capping layer 180 are provided on a substrate100.

A second vertical magnetic layer 158 may be disposed between the secondcontact magnetic layer 140 and the capping layer 180. The secondvertical magnetic layer 158 may comprise a first sub-layer 154 and asecond sub-layer 155. A first exchange-coupling layer 160 may bedisposed between the first sub-layer 154 and the second sub-layer 155. Afirst surface of the first exchange-coupling layer 160 may contact thefirst sub-layer 154 and a second surface of the first exchange-couplinglayer 160 that is opposite to the first surface may contact the secondsub-layer 155.

A magnetization direction of the first sub-layer 154 and a magnetizationdirection of the second sub-layer 155 may be exchange-coupled inanti-parallel by the first exchange-coupling layer 160.

A second exchange-coupling layer 162 may be disposed between the secondsub-layer 155 and the second contact magnetic layer 140. A first surfaceof the second exchange-coupling layer 162 may contact the secondsub-layer 155 and a second surface of the second exchange-coupling layer162 that is opposite to the first surface may contact the second contactmagnetic layer 140. A magnetization direction of the second sub-layer155 and a magnetization direction of the second contact magnetic layer140 may be exchange-coupled in anti-parallel by the secondexchange-coupling layer 162.

The second sub-layer 155 may directly contact both the firstexchange-coupling layer 160 and the second exchange-coupling layer 162.The first sub-layer 154 and the second contact magnetic layer 140 mayhave the same magnetization direction. The first and secondexchange-coupling layers 160, 162 may comprise the same material as theexchange-coupling layer 160 discussed above with reference to FIG. 1A.

The first sub-layer 154 and the second sub-layer 155 may comprisealternately and repeatedly stacked non-magnetic layers and ferromagneticlayers. This will be explained with reference to FIG. 6B.

Referring to FIG. 6B, the first sub-layer 154 may comprise the samematerial as the second sub-layer 154 that was discussed above withreference to FIG. 1B.

The second sub-layer 155 may comprise alternately and repeatedly stackedferromagnetic layers 155 aL, 155 a, 155 aU and non-magnetic layers 155bL, 155 b, 155 bU. The second surface of the exchange-coupling layer 160may contact the uppermost ferromagnetic layer 155 aU among theferromagnetic layers 155 aL, 155 a, 155 aU included in the secondsub-layer 155. The first surface of the second exchange-coupling layer162 may contact the lowermost ferromagnetic layer 155 aL among theferromagnetic layers 155 aL, 155 a, 155 aU included in the secondsub-layer 155. The uppermost and lowermost ferromagnetic materials 155aU, 155 aL may be thicker than the rest of the ferromagnetic layers 155a . The thickness of the rest of the ferromagnetic layers 155 a may besubstantially the same. For example, the lowermost and uppermostferromagnetic layers 155 aL, 155 aU may be approximately 5 Å thick andthe rest of the ferromagnetic layers 155 a may be approximately 2 Åthick. The rest of the non-magnetic layers 155 aL, 155 a, 155 aU maycomprise a same material. For example, the ferromagnetic layers 155 aL,155 a, 155 aU may comprise cobalt (Co).

The uppermost non-magnetic layer 155 bU of the second sub-layer 155 andthe lower most non-magnetic layer 155 bL of the second sub-layer 155 maycomprise a different material from the rest of the non-magnetic layers155 b . The rest of the non-magnetic layers 155 b may comprise a samematerial. For example, the lowermost and uppermost non-magnetic layers155 bL, 155 bU may comprise platinum (Pt) and the rest of thenon-magnetic layers 155 b may comprise palladium (Pd).

In a memory device according to the aforementioned fourth embodiment ofthe present inventive concept, a diffusion barrier layer may be furtherinterposed between the first contact magnetic layer 120 and the firstvertical magnetic layer 130. This will be explained with reference toFIG. 7.

FIG. 7 is a cross sectional view illustrating a magnetic memory deviceaccording to a modification of the fourth example embodiment of thepresent inventive concept.

Referring to FIG. 7, as explained above with reference to FIG. 1A, alower electrode 105, a first contact magnetic layer 120, a tunnelbarrier layer 110, a second contact magnetic layer 140 and a cappinglayer 180 can be provided on a substrate 100. A first exchange-couplinglayer 160 and a second exchange-coupling layer 162 may be providedbetween the second contact magnetic layer 140 and the capping layer 180,as explained above with reference to FIG. 6A.

A first vertical magnetic layer 132 may be provided between the firstcontact magnetic layer 120 and the lower electrode 105. A diffusionbarrier layer 172 may be disposed between the first vertical magneticlayer 132 and the first contact magnetic layer 120. The first verticalmagnetic layer 132 may be identical to the first vertical magnetic layer132 that is discussed above with reference to FIG. 2C, and the diffusionbarrier layer 172 may be identical to the first diffusion barrier layer172 that is discussed above with reference to FIG. 2A.

Different from the aforementioned modification of the fourth exampleembodiment of the present inventive concept, an exchange-coupling layermay be interposed between the first vertical magnetic layer 132 and thefirst contact magnetic layer 120 in place of the diffusion barrierlayer. This will be explained with reference to FIG. 8.

FIG. 8 is a cross sectional view illustrating a magnetic memory deviceaccording to a fifth example embodiment of the present inventiveconcept.

Referring to FIG, 8, as explained above with reference to FIG. 1A, alower electrode 105, a first contact magnetic layer 120, a tunnelbarrier layer 110, a second contact magnetic layer 140 and a cappinglayer 180 can be provided on a substrate 100. A first exchange-couplinglayer 160 and a second exchange-coupling layer 162 and a third verticalmagnetic layer 158 may be provided between the second contact magneticlayer 140 and the capping layer 180, as explained above with referenceto FIG. 6A.

A first vertical magnetic layer 133 may be provided between the lowerelectrode 105 and the first contact magnetic layer 120, and a thirdexchange-coupling layer 164 may be disposed between the first verticalmagnetic layer 133 and the first contact magnetic layer 120. Amagnetization direction of the first vertical magnetic layer 133 and amagnetization direction of the first contact magnetic layer 120 may beexchange-coupled in anti-parallel by the third exchange-coupling layer164. The first vertical magnetic layer 133 may comprise the samematerial as the first vertical magnetic layer 132 that is discussedabove with reference to FIG. 5B, and the third exchange-coupling layer164 may comprise the same material as the first exchange-coupling layer162 that is discussed above with reference to FIG. 3A.

A magnetic memory device according to the aforementioned fifth exampleembodiment of the present inventive concept may further compriseadditional exchange-coupling layer(s). This will be explained withreference to FIG. 9A.

FIG. 9A is a cross sectional view illustrating a magnetic memory deviceaccording to a sixth example embodiment of the present inventiveconcept. FIG. 9B is a cross sectional view illustrating a verticalmagnetic layer that is included in the magnetic memory device accordingto the sixth example embodiment of the present inventive concept.

Referring to FIG. 9A, as explained above with reference to FIG. 1A, alower electrode 105, a first contact magnetic layer 120, a tunnelbarrier layer 110, a second contact magnetic layer 140 and a cappinglayer 180 can be provided on a substrate 100. A vertical magnetic layer158, a first exchange-coupling layer 160 and a second exchange-couplinglayer 162 may be provided between the second contact magnetic layer 140and the capping layer 180, as explained above with reference to FIG. 6A.

A first vertical magnetic layer 138 may be provided between the firstcontact magnetic layer 120 and the lower electrode 105. A thirdexchange-coupling layer 164 may be disposed between the first verticalmagnetic layer 138 and the first contact magnetic layer 120. The thirdexchange-coupling layer 164 may comprise the same material as the thirdexchange-coupling layer 164 that is discussed above with reference toFIG. 8.

The first vertical magnetic layer 138 may comprise a first sub-layer 134and a second sub-layer 136. A magnetization direction of the firstsub-layer 134 and a magnetization direction of the first contactmagnetic layer 120 may be exchange-coupled in anti-parallel by the thirdexchange-coupling layer 164.

A fourth exchange-coupling layer 166 may be interposed between the firstsub-layer 134 and the second sub-layer 136. The fourth exchange-couplinglayer 166 may have a first surface and a second surface that areopposite to each other. The first sub-layer 134 may contact the firstsurface of the fourth exchange-coupling layer 166, and the secondsub-layer 136 may contact the second surface of the fourthexchange-coupling layer 166. A magnetization direction of the firstsub-layer 134 and a magnetization direction of the second sub-layer 136may be exchange-coupled in anti-parallel by the fourth exchange-couplinglayer 166. The second sub-layer 136 and the first contact magnetic layer120 may have a same magnetization direction. The fourthexchange-coupling layer 166 may comprise the same material as theexchange-coupling layer 160 that is discussed above with reference toFIG. 1A.

The first sub-layer 134 and the second sub-layer 136 may comprisealternately and repeatedly stacked non-magnetic and ferromagneticlayers. This will be explained with reference to FIG. 9B.

Referring to FIG. 9B, the first sub-layer 134 may comprise alternatelyand repeatedly stacked ferromagnetic layers 134 aL, 134 a, 134 aU andnon-magnetic layers 134 bL, 134 b, 134 bU. The first surface of thethird exchange-coupling layer 164 may contact the uppermostferromagnetic layer 134 aU among the ferromagnetic layers 134 aL, 134 a,134 aU that are included in the first sub-layer 134. The first surfaceof the fourth exchange-coupling layer 166 may contact the lowermostferromagnetic layer 134 aL among the ferromagnetic layers 134 aL, 134 a,134 aU that are included in the first sub-layer 134. The uppermost andlowermost ferromagnetic materials 134 aU, 134 aL may be thicker than therest of the ferromagnetic layers 134 a . The thickness of the rest ofthe ferromagnetic layers 134 a may be substantially the same. Forexample, the lowermost and uppermost ferromagnetic layers 134 aL, 134 aUmay be approximately 5 Å thick and the rest of the ferromagnetic layers134 a may be approximately 2 Å thick. The ferromagnetic layers 134 aL,134 a, 134 aU may comprise a same material. For example, theferromagnetic layers 134 aL, 134 a, 134 aU may comprise cobalt (Co).

The uppermost non-magnetic layer 134 bU of the first sub-layer 134 andthe lowermost non-magnetic layer 134 bL of the first sub-layer 134 maycomprise a different material from the rest of the non-magnetic layers134 b . The rest of the non-magnetic layers 134 b may comprise a samematerial. For example, the lowermost and uppermost non-magnetic layers134 bL, 134 bU may comprise platinum (Pt) and the rest of thenon-magnetic layers 134 b may comprise palladium (Pd).

The second sub-layer 136 may comprise alternately and repeatedly stackedferromagnetic layers 136 a, 136 aU and non-magnetic layers 136 b, 136bU. The second surface of the fourth exchange-coupling layer 166 maycontact the uppermost ferromagnetic layer 136 aU among the ferromagneticlayers 136 a, 136 aU included in the second sub-layer 136. The uppermostferromagnetic layer 134 aU may be thicker than the rest of theferromagnetic layers 136 a included in the second sub-layer 136. Thethickness of the rest of the ferromagnetic layers 136 a may besubstantially the same. For example, the uppermost ferromagnetic layers136 aU may be approximately 5 Å thick and the rest of the ferromagneticlayers 136 a may be approximately 2 Å thick. The uppermost ferromagneticlayers 136 aU may comprise the same material as the rest of theferromagnetic layers 136 a . For example, the ferromagnetic layers 136aU, 136 a may comprise cobalt (Co).

The uppermost non-magnetic layer 136 bU of the second sub-layer 136 maycomprise a different material from the rest of the non-magnetic layers136 b . The rest of the non-magnetic layers 136 b may comprise a samematerial. For example, the uppermost non-magnetic layers 136 bU maycomprise platinum (Pt) and the rest of the non-magnetic layers 136 b maycomprise palladium (Pd).

Magnetic memory devices according to the aforementioned exampleembodiments of the present inventive concept can be implemented invarious forms of semiconductor packages. For example, magnetic memorydevices according to example embodiments of the present inventiveconcept can be packaged by various packaging methods such as Package onPackage (PoP), Ball Grid Arrays (BGAs), Chip Scale Packages (CSPs),Plastic Leaded Chip Carrier (PLCC), Plastic Dual In-Line Package (PDIP),Die in Waffle Pack, Die in Wafer Form, Chip On Board (COB), Ceramic DualIn-Line Package (CERDIP), Plastic Metric Quad Flat Pack (MQFP), ThinQuad Flat Pack (TQFP), Small Outline (SOIC), Shrink Small OutlinePackage (SSOP), Thin Small Outline Package (TSOP), Thin Quad Flat Pack(TQFP), System In Package (SIP), Multi Chip Package (MCP), Wafer-levelFabricated Package (WFP) and/or Wafer-Level Processed Stack Package(WSP). The packages mounting magnetic memory devices according toexample embodiments of the present inventive concept may furthercomprise controllers and/or logic devices to control the semiconductordevices.

FIG. 10 is a block diagram illustrating an electronic system thatincludes a magnetic memory device according to example embodiments ofthe present inventive concept.

Referring to FIG. 10, an electronic system 1100 according to exampleembodiments of the present invention may comprise a controller 1110, aninput/output device (I/O) 1120, a memory device 1130, an interface 1140and a bus 1150. The controller 1110, the input/output device 1120, thememory device 1130 and/or the interface 1140 can be coupled to eachother through the bus 1150. The bus 1150 corresponds to a datacommunication path.

The controller 1100 may comprise at least one selected from the groupconsisting of a microprocessor, a digital signal processor, amicrocontroller and a logic device performing similar functions to theforegoing devices. The input/output device 1120 may include keypad,keyboard and/or display devices. The memory device 1130 may store dataand/or instructions. The memory device 1130 may comprise at least onemagnetic memory device according to example embodiments of the presentinventive concept. Further, the memory device 1130 may further comprisedifferent forms of semiconductor memory devices such as Flash memory,DRAM and/or SRAM devices. The interface 1140 may send data tocommunication network or receive data from the communication network.The interface 1140 may be wireless or wired. For example, the interface1140 may include an antenna or wired/wireless transceiver. Although notillustrated herein, the electronic system 1100 may further comprise ahigh speed DRAM and/or SRAM as an operation memory to improve operationof the controller 1110.

The electronic system 1100 may be applied to Personal Digital Assistant(PDA), portable computer, web tablet, wireless phone, mobile phone,digital music player, memory card, or various kinds of electronicequipment that can wirelessly send and receive data.

FIG. 11 is a block diagram illustrating a memory card including amagnetic memory device according to example embodiments of the presentinventive concept.

Referring to FIG. 11, a memory card 1200 according to exampleembodiments of the present inventive concept may comprise a memorydevice 1210. The memory device 1210 may comprise at least one magneticmemory device disclosed herein according to example embodiments of thepresent inventive concept. Further, the memory device 1210 may furthercomprise different forms of semiconductor memory devices such as DRAMand/or SRAM devices. The memory card 1200 may further comprise a memorycontroller 1220 controlling data exchange between a host and the memorydevice 1210.

The memory controller 1220 may comprise a processing unit to controloverall operation of the memory card. The memory controller 1220 mayfurther comprise an SRAM 1221 used as an operation memory of the memorycontroller 1220. Further, the memory controller 1220 may furthercomprise a host interface 1223 and a memory interface 1225.

The host interface 1223 may be equipped with a data exchange protocolbetween the memory card 1200 and a host device. The memory interface1225 may couple the memory controller 1220 with the memory device 1210.The memory controller 1220 may further comprise an error correctionblock (ECC) 1224. The error correction block 1224 may detect and correcterrors in the read-out data from the memory device 1210. Although notillustrated herein, the memory card 1200 may further comprise a ROMdevice storing code data for interfacing with the host. The memory card1200 may be used as a portable data storage card. Conversely, the memorycard 1200 can be implemented as solid-state disks, which can replaceconventional hard disks of computer systems.

Although a few example embodiments of the present inventive concept havebeen described with reference to the enclosed drawings, those who areskilled in the art will readily appreciate that various modificationsare possible from the example embodiments without materially departingfrom the novel teachings and advantages of the present inventiveconcept. Accordingly, the example embodiments disclosed hereinabove areto explain the present inventive concept and should not be used to limitthe meaning or the scope of the invention defined in the claims.

What is claimed is:
 1. A magnetic memory device comprising: a referencelayer comprising; a first contact magnetic layer having a firstsaturation magnetization; a vertical magnetic layer having perpendicularmagnetization; and an exchange coupling layer disposed between the firstcontact magnetic layer and the vertical magnetic layer; a free layercomprising a second contact magnetic layer having a second saturationmagnetization; and a tunnel barrier layer disposed between the freelayer and the reference layer, wherein the first saturationmagnetization is higher than the second saturation magnetization, andwherein the vertical magnetic layer comprises a stacked ferromagneticlayer and non-ferromagnetic layer.
 2. The magnetic memory device ofclaim 1, wherein the first contact magnetic layer comprises CoFeB. 3.The magnetic memory device of claim 2, wherein the second contactmagnetic layer comprises CoFeB.
 4. The magnetic memory device of claim1, wherein a thickness of the first contact magnetic layer is less thanthat of the vertical magnetic layer.
 5. The magnetic memory device ofclaim 1, wherein the vertical magnetic layer comprises at least one ofCr, Pt, Pd, or Ir.
 6. The magnetic memory device of claim 1, wherein athickness of the exchange coupling layer is less than a thickness of thetunnel barrier layer.
 7. The magnetic memory device of claim 1, whereinthe free layer further comprises a non-magnetic layer.
 8. The magneticmemory device of claim 1, wherein the exchange coupling layer directlycontacts an uppermost ferromagnetic layer of the vertical magneticlayer.
 9. The magnetic memory device of claim 8, wherein the uppermostferromagnetic layer of the vertical magnetic layer is thicker than theremainder of the ferromagnetic layers of the vertical magnetic layer.10. The magnetic memory device of claim 1, wherein an uppermostnon-ferromagnetic layer of the vertical magnetic layer comprises adifferent material than the remainder of the non-ferromagnetic layers ofthe vertical magnetic layer.
 11. The magnetic memory device of claim 1,wherein the vertical magnetic layer comprises alternately and repeatedlystacked ferromagnetic layers and non-ferromagnetic layers.
 12. Amagnetic memory device comprising: a reference layer comprising; a firstcontact magnetic layer that comprises a CoFeB layer; a first verticalmagnetic layer; and a first exchange coupling layer disposed between thefirst contact magnetic layer and the first vertical magnetic layer; afree layer comprising: a second contact magnetic layer that comprises aCoFeB layer; a second vertical magnetic layer; and a second exchangecoupling layer disposed between the second contact magnetic layer andthe second vertical magnetic layer; and a tunnel barrier layer disposedbetween the free layer and reference layer, wherein the first and secondvertical magnetic each comprise alternately and repeatedly stackedferromagnetic layers and non-magnetic layers.
 13. The magnetic memorydevice of claim 12, wherein the second contact magnetic layer comprisesCoFeB.
 14. The magnetic memory device of claim 12, wherein a thicknessof the first contact magnetic layer is less than that of the firstvertical magnetic layer.
 15. The magnetic memory device of claim 12,wherein the first vertical magnetic layer comprises at least one of Cr,Pt, Pd, or Ir.
 16. The magnetic memory device of claim 12, wherein athickness of the first exchange coupling layer is less than that of thetunnel barrier layer.
 17. The magnetic memory device of claim 12,wherein the free layer further comprises a non-magnetic layer.